help signrank, help signtest dialogs: signrank signtest
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Title
[R] signrank -- Equality tests on matched data
Syntax
Wilcoxon matched-pairs signed-ranks test
signrank varname = exp [if] [in]
Sign test of matched pairs
signtest varname = exp [if] [in]
by is allowed with signrank and signtest; see [D] by.
Menu
signrank
Statistics > Nonparametric analysis > Tests of hypotheses > Wilcoxon
matched-pairs signed-rank test
signtest
Statistics > Nonparametric analysis > Tests of hypotheses > Test
equality of matched pairs
Description
signrank tests the equality of matched pairs of observations by using the
Wilcoxon matched-pairs signed-ranks test (Wilcoxon 1945). The null
hypothesis is that both distributions are the same.
signtest also tests the equality of matched pairs of observations
(Arbuthnott 1712, but better explained by Snedecor and Cochran 1989) by
calculating the difference between varname and the expression. The null
hypothesis is that the median of the differences is zero; no further
assumptions are made about the distributions. This, in turn, is
equivalent to the hypothesis that the true proportion of positive
(negative) signs is one-half.
For equality tests on unmatched data, see [R] ranksum.
Examples
. webuse fuel
. signrank mpg1 = mpg2
. signtest mpg1 = mpg2
Saved results
signrank saves the following in r():
Scalars
r(N_neg) number of negative comparisons
r(N_pos) number of positive comparisons
r(N_tie) number of tied comparisons
r(sum_pos) sum of the positive ranks
r(sum_neg) sum of the negative ranks
r(z) z statistic
r(Var_a) adjusted variance
signtest saves the following in r():
Scalars
r(N_neg) number of negative comparisons
r(N_pos) number of positive comparisons
r(N_tie) number of tied comparisons
r(p_2) two-sided probability
r(p_neg) one-sided probability of negative comparison
r(p_pos) one-sided probability of positive comparison
References
Arbuthnott, J. 1712. An argument for divine providence, taken from the
constant regularity observed in the births of both sexes.
Philosophical Transactions 27: 186-190.
Snedecor, G. W., and W. G. Cochran. 1989. Statistical Methods. 8th ed.
Ames, IA: Iowa State University Press.
Wilcoxon, F. 1945. Individual comparisons by ranking methods. Biometrics
1: 80-83.
Also see
Manual: [R] signrank
Help: [R] ranksum, [R] ttest
